A small digital closed-loop fiber-optic gyroscope half-wave voltage debugging method

Abstract

This invention relates to the field of fiber optic gyroscope technology and discloses a method for adjusting the half-wave voltage of a small digital closed-loop fiber optic gyroscope. First, the transit time τ of the fiber optic gyroscope is determined based on the length of the fiber loop. With a period of 4τ, an FPGA chip controls a D / A converter to output an analog signal, and a drive circuit controls a Y-waveguide to output a set waveform. Within each 4τ period, the FPGA chip controls the A / D converter to sequentially acquire the voltage value of the detector's output electrical signal within each τ time interval. Based on the voltage value, the half-wave voltage error ΔD of the Y-waveguide within the 4τ period is calculated. 2π According to ΔD 2π The FPGA chip continuously adjusts the reference voltage of the D / A converter and outputs the digital value corresponding to the current half-wave voltage through the external interface; it determines the value when the digital value is stable and converts it into the corresponding half-wave voltage of the Y-waveguide. The debugging method of this invention is simple, greatly simplifying the debugging process of small fiber optic gyroscopes and improving production efficiency.

Description

Technical Field

[0001] This invention relates to the field of fiber optic gyroscope technology, and more specifically, to a method for adjusting the half-wave voltage of a small digital closed-loop fiber optic gyroscope. Background Technology

[0002] Fiber optic gyroscopes are angular rate sensors based on Sagnac. Due to their low cost, simple manufacturing process, high reliability, and strong resistance to shock and vibration, they have become one of the mainstream sensors. The determination of the half-wave voltage of the multifunctional integrated optical device (Y-waveguide) in the fiber optic gyroscope plays a crucial role in the gyroscope's debugging process.

[0003] Modulation methods for fiber optic gyroscopes typically include square wave modulation and four-state modulation. Small digital closed-loop fiber optic gyroscopes, due to their short fiber loop length, generally use square wave modulation. Square wave modulation usually requires determining an approximate value for the Y-waveguide half-wave voltage during the fiber optic gyroscope manufacturing process. Determining this value necessitates repeatedly modifying the digital value of the Y-waveguide half-wave voltage in the FPGA program and repeatedly measuring the output waveform of the detector in the fiber optic gyroscope using an oscilloscope to confirm the reasonableness of the Y-waveguide half-wave voltage. This entire process is cumbersome and detrimental to the debugging of the fiber optic gyroscope. Summary of the Invention

[0004] The purpose of this invention is to address the technical problems existing in the prior art by providing a method for adjusting the half-wave voltage of a small digital closed-loop fiber optic gyroscope. This method is simple and greatly simplifies the adjustment process of small fiber optic gyroscopes, thereby improving production efficiency.

[0005] To address the problems mentioned above, the technical solution adopted by this invention is as follows:

[0006] This invention provides a method for adjusting the half-wave voltage of a small digital closed-loop fiber optic gyroscope. The fiber optic gyroscope includes a light source, a coupler, a Y-waveguide, a detector, an A / D converter, a driving circuit, a D / A converter, an FPGA chip, and a fiber optic ring. The light signal emitted by the light source is coupled by the coupler, modulated by the Y-waveguide, and then enters the fiber optic ring where it interferes and generates a phase difference. The interfered light signal passes sequentially through the Y-waveguide and the coupler before being fed back to the detector, which converts the received light signal into an electrical signal.

[0007] The debugging method includes:

[0008] The transit time τ of the fiber optic gyroscope is determined based on the length of the fiber optic loop.

[0009] With a time period of 4τ, the FPGA chip controls the D / A converter to output an analog signal, and controls the Y waveguide to output a set waveform through the drive circuit;

[0010] Within each 4τ cycle, the FPGA chip controls the A / D converter to sequentially acquire the voltage value of the detector output electrical signal within each τ time period;

[0011] Based on the voltage value, calculate the half-wave voltage error ΔD of the Y-waveguide within a 4τ period. 2π ;

[0012] According to ΔD 2π The FPGA chip continuously adjusts the reference voltage of the D / A converter and outputs the digital value corresponding to the current half-wave voltage through the external interface.

[0013] Determine the value of the digital quantity when it is stable, and convert it into the corresponding half-wave voltage of the Y-waveguide.

[0014] Furthermore, the waveform is set with a 4τ period as the horizontal axis and the amplitude as the vertical axis, and the amplitude of the waveform is set to 0 in each τ time period. 0, As shown in formula (1):

[0015]

[0016] The resulting phase difference is:

[0017]

[0018] Furthermore, assume that the number of sampling points within a 4τ period is 4n, and the sampled electrical signal is d. i (i=1,2,3...,4n), then the collected voltage values ​​are recorded as D1, D2, D3, D4, as shown in formula (3):

[0019]

[0020] Furthermore, the half-wave voltage error ΔD 2π As shown in the formula:

[0021] ΔD 2π =D1+D4-D2-D3.

[0022] Furthermore, when ΔD 2π If ΔD < 0, it indicates that the half-wave voltage is less than 2π, so increase the reference voltage of the D / A converter; when ΔD 2π If ΔD > 0, it indicates that the half-wave voltage is greater than 2π, so the reference voltage of the D / A converter should be reduced; when ΔD 2π =0, which means the half-wave voltage is equal to 2π.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The debugging method of the present invention controls the D / A converter through the FPGA chip, controls the Y waveguide to output the set waveform, and controls the A / D converter to collect the voltage value. Based on the calculated half-wave voltage error, the reference voltage output digital quantity of the D / A converter is adjusted. When the digital quantity is stable, the half-wave voltage is obtained. Through the control of the FPGA chip, the digital quantity corresponding to the half-wave voltage can be automatically output through the external interface. It is not necessary to test the detector output through an oscilloscope. The debugging method is simple and efficient, which greatly simplifies the debugging process of small fiber optic gyroscopes and helps to improve production efficiency.

[0025] (2) The amplitude of the set wavelength in this invention is 0 in each time period τ. 0, Fiber optic gyroscopes operate alternately in At the point, the reset point occurs The point is consistent with the actual operating point of the fiber optic gyroscope, ensuring the reliability of the fiber optic gyroscope's operation.

[0026] (3) The present invention adjusts the reference voltage of the D / A converter according to the half-wave voltage error, so that the output digital quantity is accurate and reliable, and the obtained half-wave voltage value is also reliable. The adjustment process is gradual, simple and reliable. Attached Figure Description

[0027] To more clearly illustrate the solutions in this invention, a brief introduction to the accompanying drawings used in the description of the embodiments will be provided below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort. Wherein:

[0028] Figure 1 This is a schematic diagram of the small digital closed-loop fiber optic gyroscope of the present invention.

[0029] Figure 2 This is a flowchart of the method for adjusting the half-wave voltage of a small digital closed-loop fiber optic gyroscope according to the present invention.

[0030] Figure 3 A schematic diagram illustrating the waveform settings for this invention.

[0031] Figure 4 This is a schematic diagram of the modulation phase point and the set waveform of the present invention (wherein, the schematic diagram of the modulation phase point is a, and the schematic diagram of the set waveform is b). Detailed Implementation

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, terms such as “length,” “width,” “upper,” “lower,” “left,” “right,” “front,” “rear,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer” indicate orientations or positions based on the orientations or positions shown in the accompanying drawings and are for ease of description only, and should not be construed as limiting the technical solution.

[0033] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a particular order. In the specification, claims, and accompanying drawings of this invention, when an element is referred to as "fixed to," "mounted to," "disposed of," or "connected to" another element, it may be directly or indirectly located on that other element. For example, when an element is referred to as "connected to" another element, it may be directly or indirectly connected to that other element.

[0034] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] See Figure 1 As shown, the present invention provides a method for adjusting the half-wave voltage of a small digital closed-loop fiber optic gyroscope. The fiber optic gyroscope includes a light source 10, a coupler 20, a Y-waveguide 30, a detector 40, an A / D converter 50, a drive circuit 60, a D / A converter 70, an FPGA chip 80, and a fiber optic ring 90.

[0036] The light signal emitted by the light source 10 is coupled by the coupler 20, modulated by the Y-waveguide 30, and then enters the fiber optic ring 90, where it interferes and generates a phase difference. After interfering in the fiber optic ring 90, the light signal passes sequentially through the Y-waveguide 30 and the coupler 20 before returning to the detector 40. The detector 40 is responsible for converting the received light signal into an electrical signal. The FPGA chip 80 controls the A / D converter 50 to acquire the voltage value of the electrical signal from the detector 40. After calculating the acquired voltage value, the FPGA chip 80 controls the D / A converter 70 to output an analog signal, which drives the Y-waveguide 30 to output a modulated light signal through the drive circuit 60.

[0037] Specifically, the FPGA chip 80 is responsible for the timing, calculation, and connection to external interfaces of the entire control, forming a closed loop.

[0038] See Figure 2 As shown, the specific steps of this debugging method include the following:

[0039] Step S1: Determine the transit time τ of the fiber optic gyroscope based on the length of the fiber optic loop 90.

[0040] Specifically, the transit time of a fiber optic gyroscope is the time required for an optical signal to propagate once in the fiber optic loop 90. In other words, the transit time τ of the fiber optic gyroscope can be approximately determined based on the length of the fiber optic loop 90.

[0041] Step S2: Based on the determined transit time τ, with a period of 4τ, the FPGA chip 80 controls the D / A converter 70 to output an analog signal, and controls the Y waveguide 30 to output a set waveform through the drive circuit 60, repeating the cycle.

[0042] Specifically, Figure 3 As shown, the horizontal axis represents the 4τ period, and the vertical axis represents the amplitude. The waveform is set to have an amplitude of 0, ... 0、 Phase modulation φ of the fiber optic gyroscope m (t), expressed by formula (1) as follows:

[0043]

[0044] Therefore, the resulting phase difference is:

[0045]

[0046] Where m = 0, 1, 2, 3…, and the modulation phase is… Figure 4 As shown in a, Figure 4 b represents the electrical signal output by the corresponding detector 40.

[0047] In this embodiment, since small digital closed-loop fiber optic gyroscopes typically operate alternately in... At the point, the reset point occurs On the point, through Figure 2 The set waveform, the modulation phase point is as follows Figure 3 As shown, the generated modulation point occurs exactly at the above operating point and reset point, which is consistent with the actual operating point of the fiber optic gyroscope.

[0048] Step S3: Within each 4τ cycle, the FPGA chip 80 controls the A / D converter 50 to sequentially acquire the voltage values ​​of the output electrical signal of the detector 40 in each τ time period, and record them as D1, D2, D3, and D4.

[0049] Specifically, assume that the number of sampling points within a 4τ period is 4n, and the sampled electrical signal can be represented as d. i (i=1, 2, 3, ..., 4n), then the obtained voltage values ​​are shown in formula (3):

[0050]

[0051] Step S4: Based on the voltage value, calculate the half-wave voltage error ΔD of the Y-waveguide 30 within a 4τ period. 2π The mathematical expression is:

[0052] ΔD 2π =D1+D4-D2-D3.

[0053] Specifically, the voltage of four adjacent cycles acquired by the A / D converter 50 is affected by the half-wave voltage of the Y-waveguide 30. The digital value corresponding to the 2π voltage of the Y-waveguide is determined based on the number of bits in the D / A converter 70. For example, in a 16-bit D / A converter 70, 2^16 = 65536 represents the digital value corresponding to the 2π voltage; in a 14-bit D / A converter 70, 2^14 = 16384 represents the digital value corresponding to the 2π voltage. The initial reference voltage of the D / A converter 70 is set to half of its maximum reference voltage.

[0054] Step S5: Based on the half-wave voltage error ΔD 2π The FPGA chip 80 continuously adjusts the reference voltage of the D / A converter 70 and continuously outputs the digital quantity corresponding to the current half-wave voltage through the external interface.

[0055] Specifically, when the half-wave voltage is too large, ΔD 2π If the value is less than 0, it indicates that the half-wave voltage is less than 2π, so the reference voltage of the D / A converter 70 should be increased. When the deviation is small, ΔD 2π If the value is greater than 0, it indicates that the half-wave voltage is greater than 2π, thus reducing the reference voltage of the D / A converter 70. ΔD only applies when they are equal. 2π =0, half-wave voltage equals 2

[0056] π gradually converges during the adjustment process.

[0057] In this embodiment, since the fiber optic gyroscope generates a 2π reset when it is working, the reference voltage is modified to control it. The half-wave voltage is compared with the 2π reset voltage. Only when the half-wave voltage is equal to 2π will it not affect the output of the fiber optic gyroscope, and the digital quantity corresponding to the current half-wave voltage will be output.

[0058] Step S6: Observe the value corresponding to the gradual stabilization of the digital quantity through the external interface, and convert it to obtain the half-wave voltage of the corresponding Y-waveguide.

[0059] The half-wave voltage debugging method provided by this invention is fully automated within the FPGA chip 80. The FPGA chip 80 is responsible for controlling the acquisition of the A / D converter 50, the output of the D / A converter 70, and calculating ΔD. 2π Adjusting the reference voltage of the D / A converter 70 and continuously outputting the digital value corresponding to the half-wave voltage through the external interface is a simple process that does not require repeated manual debugging, measurement, and calculation. This greatly simplifies the debugging process of small fiber optic gyroscopes and helps improve production efficiency.

[0060] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A small digital closed-loop fiber-optic gyroscope half-wave voltage debugging method, characterized in that: The fiber-optic gyroscope comprises a light source, a coupler, a Y waveguide, a detector, an A / D converter, a driving circuit, a D / A converter, an FPGA chip and a fiber-optic ring; the light source emits light signals which, after coupling by the coupler, are modulated by the Y waveguide and then enter the fiber-optic ring to generate a phase difference by interference; the light signals after interference are fed back to the detector in turn through the Y waveguide and the coupler; the detector converts the received light signals into electric signals; The debugging method comprises: determining a transit time τ of the fiber-optic gyroscope according to the length of the fiber-optic ring; controlling the D / A converter to output an analog signal by the FPGA chip with a period of 4τ to control the Y waveguide to output with the determined set waveform; in each 4τ period, controlling the A / D converter to collect the voltage value of the electric signal output by the detector in each τ time in turn by the FPGA chip; According to the voltage value, the half-wave voltage error ΔD of the Y waveguide in 4τ period is calculated 2π ; According to the value of ΔD 2π , the FPGA chip continuously adjusts the reference voltage of the D / A converter and constantly outputs the digital quantity corresponding to the current half-wave voltage through the external interface. determining the value when the digital quantity is stable and converting it into the corresponding half-wave voltage of the Y waveguide.

2. The method according to claim 1, wherein the method is characterized in that: The set waveform has a time interval of 4τ as the horizontal axis and amplitude as the vertical axis. The amplitude of the set waveform is 0 in each τ time interval. 0, Phase modulation φ of the fiber optic gyroscope m (t), as shown in formula (1): wherein m is a constant of 0, 1, 2, 3…, and the generated phase difference is:

3. The method according to claim 1 or 2, wherein: Assuming the number of sampling points in 4τ period is 4n, and the sampling electric signal is d i The collected voltage values are recorded as D1, D2, D3, and D4, as shown in formula (3): wherein i=1, 2, 3…4n.

4. The method according to claim 3, wherein the method further comprises: The half-wave voltage error ΔD 2π As shown in the formula: ΔD 2π = D1+D4-D2-D3.

5. The method according to claim 1 or 4, wherein: When ΔD 2π <0, it indicates that the half-wave voltage is less than 2π, so the reference voltage of the D / A converter is increased; when ΔD 2π >0, it indicates that the half-wave voltage is greater than 2π, so the reference voltage of the D / A converter is decreased; when ΔD 2π =0, it indicates that the half-wave voltage is equal to 2π.

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